Allow attachInterrupt() on NMI pin (PA08 on ATSAMD21E)

Author: PaintYourDragon

cores/arduino/WInterrupts.c

@@ -62,57 +62,86 @@ void attachInterrupt(uint32_t pin, voidFuncPtr callback, uint32_t mode)
 #else
   EExt_Interrupts in = digitalPinToInterrupt(pin);
 #endif
-  if (in == NOT_AN_INTERRUPT || in == EXTERNAL_INT_NMI)
-    return;
+  if (in == NOT_AN_INTERRUPT) return;
 
   if (!enabled) {
     __initialize();
     enabled = 1;
   }
 
-  // Enable wakeup capability on pin in case being used during sleep
-  EIC->WAKEUP.reg |= (1 << in);
+  if (in == EXTERNAL_INT_NMI) {
+    EIC->NMIFLAG.bit.NMI = 1; // Clear flag
+    switch (mode) {
+      case LOW:
+        EIC->NMICTRL.bit.NMISENSE = EIC_NMICTRL_NMISENSE_LOW;
+        break;
 
-  // Assign pin to EIC
-  pinPeripheral(pin, PIO_EXTINT);
+      case HIGH:
+        EIC->NMICTRL.bit.NMISENSE = EIC_NMICTRL_NMISENSE_HIGH;
+        break;
 
-  // Assign callback to interrupt
-  callbacksInt[in] = callback;
+      case CHANGE:
+        EIC->NMICTRL.bit.NMISENSE = EIC_NMICTRL_NMISENSE_BOTH;
+        break;
 
-  // Look for right CONFIG register to be addressed
-  if (in > EXTERNAL_INT_7) {
-    config = 1;
-  } else {
-    config = 0;
-  }
+      case FALLING:
+        EIC->NMICTRL.bit.NMISENSE = EIC_NMICTRL_NMISENSE_FALL;
+        break;
 
-  // Configure the interrupt mode
-  pos = (in - (8 * config)) << 2;
-  switch (mode)
-  {
-    case LOW:
-      EIC->CONFIG[config].reg |= EIC_CONFIG_SENSE0_LOW_Val << pos;
-      break;
+      case RISING:
+        EIC->NMICTRL.bit.NMISENSE = EIC_NMICTRL_NMISENSE_RISE;
+        break;
+    }
 
-    case HIGH:
-      EIC->CONFIG[config].reg |= EIC_CONFIG_SENSE0_HIGH_Val << pos;
-      break;
+    // Assign callback to interrupt
+    callbacksInt[EXTERNAL_INT_NMI] = callback;
 
-    case CHANGE:
-      EIC->CONFIG[config].reg |= EIC_CONFIG_SENSE0_BOTH_Val << pos;
-      break;
+  } else { // Not NMI, is external interrupt
 
-    case FALLING:
-      EIC->CONFIG[config].reg |= EIC_CONFIG_SENSE0_FALL_Val << pos;
-      break;
+    // Enable wakeup capability on pin in case being used during sleep
+    EIC->WAKEUP.reg |= (1 << in);
 
-    case RISING:
-      EIC->CONFIG[config].reg |= EIC_CONFIG_SENSE0_RISE_Val << pos;
-      break;
-  }
+    // Assign pin to EIC
+    pinPeripheral(pin, PIO_EXTINT);
+
+    // Look for right CONFIG register to be addressed
+    if (in > EXTERNAL_INT_7) {
+      config = 1;
+    } else {
+      config = 0;
+    }
+
+    // Configure the interrupt mode
+    pos = (in - (8 * config)) << 2;
+    switch (mode)
+    {
+      case LOW:
+        EIC->CONFIG[config].reg |= EIC_CONFIG_SENSE0_LOW_Val << pos;
+        break;
+
+      case HIGH:
+        EIC->CONFIG[config].reg |= EIC_CONFIG_SENSE0_HIGH_Val << pos;
+        break;
+
+      case CHANGE:
+        EIC->CONFIG[config].reg |= EIC_CONFIG_SENSE0_BOTH_Val << pos;
+        break;
+
+      case FALLING:
+        EIC->CONFIG[config].reg |= EIC_CONFIG_SENSE0_FALL_Val << pos;
+        break;
 
-  // Enable the interrupt
-  EIC->INTENSET.reg = EIC_INTENSET_EXTINT(1 << in);
+      case RISING:
+        EIC->CONFIG[config].reg |= EIC_CONFIG_SENSE0_RISE_Val << pos;
+        break;
+    }
+
+    // Enable the interrupt
+    EIC->INTENSET.reg = EIC_INTENSET_EXTINT(1 << in);
+
+    // Assign callback to interrupt
+    callbacksInt[in] = callback;
+  }
 }
 
 /*
@@ -125,13 +154,16 @@ void detachInterrupt(uint32_t pin)
 #else
   EExt_Interrupts in = digitalPinToInterrupt(pin);
 #endif 
-  if (in == NOT_AN_INTERRUPT || in == EXTERNAL_INT_NMI)
-    return;
+  if (in == NOT_AN_INTERRUPT) return;
 
-  EIC->INTENCLR.reg = EIC_INTENCLR_EXTINT(1 << in);
+  if(in == EXTERNAL_INT_NMI) {
+    EIC->NMICTRL.bit.NMISENSE = 0; // Turn off detection
+  } else {
+    EIC->INTENCLR.reg = EIC_INTENCLR_EXTINT(1 << in);
 
-  // Disable wakeup capability on pin during sleep
-  EIC->WAKEUP.reg &= ~(1 << in);
+    // Disable wakeup capability on pin during sleep
+    EIC->WAKEUP.reg &= ~(1 << in);
+  }
 }
 
 /*
@@ -154,3 +186,12 @@ void EIC_Handler(void)
     }
   }
 }
+
+/*
+ * NMI Interrupt Handler
+ */
+void NMI_Handler(void)
+{
+  if (callbacksInt[EXTERNAL_INT_NMI]) callbacksInt[EXTERNAL_INT_NMI]();
+  EIC->NMIFLAG.bit.NMI = 1; // Clear interrupt
+}